At this point I copied the neck from another reference image, and the back of the head from yet another. Use Liquify where needed to nudge things into place, and erase to smooth the transition between layers.

The picture that I had as reference for the back of the head was actually taken from a different person and the skintone didn't match. It's common that you'll have to piece together the facial texture from several sources and getting the skin from each piece to match can be a real pain. But there's one quick trick I've found that works most of the time.

Ok, so you've pasted the piece onto a new layer. Go to Image > Adjust > Match Color and a window will come up. In the bottom portion of the window is Source and Layer. From the Source drop-down choose the image you're working on now. Now from Layer pick a layer that you want to match.

Since the layer I added had hair, and skin, I want to match it to another layer that has both hair and skin (the one I sampled from was the forehead/top hairline). This way it will match better.

If you need to, adjust the Luminance, Fade, etc. Match color doesn't always work, but it usually gets pretty close.

So just continue grabbing pieces of photo ref, use match color and Liquify when needed, and check 3dsmax frequently to make sure things are matching up.

This is the base texture I ended up with. At this point I *could* be done. But I'm not. Now I'm going to go in and manually paint in some details, sharpen some areas, and apply general touch-ups all over. Since this is a low-res texture, and the character will usually be seen from a distance larpening some features usually gets a better result.

At this point, I selected all of my face layers and merged them together. I created a new layer ontop of it (but still below the UV ref layer) and selected the Painbrush tool. In the options set the Opacity to around 50% and choose one of the solid round brushes.

Holding down the Alt key will switch your tool to the eyedropper so you can pick colors quickly and easily. While painting you will frequently need to pick colors from the image so just keep your finger on the Alt key for easy switching.

The texture as it currently is, is freaky on the forehead when I actually check it in 3dsmax, so the first thing that I touched up was the forehead.

Hold down Alt and pick up some skin tone. Now just paint over the problem areas with larger brushes. Since the brush is set to 50% opacity, you can get in-between colors by doing a singe brush pass over an area, and then using Alt to pick the new color. Do this over and over and make layers.

For smaller details switch to a smaller brush size. I defined the hair line by just picking a black-ish color from the hair and painting in better hair roots.

After the forehead, I turned my attention to the eyes. Using the eyedropper I picked the 'white' of the eye. But then I went into the color picker and wen brigher (still not actual 'white' but a ligher color then the one there) and painted in the whites of the eyes better.

I picked ligher skin tones and increased the contrast around the eyes and the wrinkles, and I sharpened up the eye brows.

I checked the progress in 3dsmax and deiced I still needed more definition to the forehead. Went back in and did some more touch-ups to the hair line and checked it in max.

My plan is to make some alpha poly hair once I'm down with all the textures, so this is just the underhair, but it still needs to look good on the edges and hairlines.

As another example, just compare the eyes of this version with the texture before any manual touch-ups (just above). The eyes stand out much more now. So even small touch-ups can make a big difference.

Touch-ups on the nose and lips can make a BIG difference in the final look so they're important.

Usually the first thing I do is fix the nostrils (they usually aren't shaped correctly to appear in the right location on the actual model. Just make adjustments, save, check, and repeat until they look correct in max).

I made the base/underside of the nose darker, increased the contrast between the bridge of the nose, and the shadow on the sides of it. I adjusted the highlights on the outer nostrils, and drew in the crase where the outer nostril meets the cheek.

For the lips, I find it's best to make the top-lip almost solid dark. I drew in highlights along the top of teh lip, and the highlights on the lower-lip. I also darkened up and created a more solid border below the bottom lip.

I find that I often get better results on skin if I use a small brush (usually the solid round 3) and 'scribble' in some areas. You don't want a really smooth look on the skin because it'll look fake.

Again - save often and check your progress in 3dsmax. Already the face is looking much more defined then it was before the touch-ups with minimal work.